Mold structures, and method of transfer of fine structures

ABSTRACT

A mold and a pattern transfer method using the same for a nanoprinting technology. The mold can be released from a substrate accurately and easily. The mold, which is used for forming a fine pattern on a substrate using a press machine, comprises a release mechanism.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to a nanoprint transfer method forforming a fine structure on a substrate using a mold comprising aheating and a pressure-applying mechanism.

[0003] 2. Background Art

[0004] In recent years, the semiconductor integrated circuits arebecoming increasingly finer and more integrated. To cope with such sizereductions and increased levels of integration, the accuracy of thephotolithography equipment as a pattern transfer technology has beencontinuously improved. However, the processing method now involves ascale close to that of the wavelength of the photolithographic lightsource, and the lithography technology is close to its limit. As aresult, in order to allow for further reductions in size and achievehigher accuracy, electron beam lithography equipment, which is a type ofcharged-particle beam equipment, has come to be used more often thanphotolithography technology.

[0005] When patterns are formed using an electron beam, in contrast tothe one-shot exposure method whereby an i-line or excimer laser lightsource is used for forming patterns, a mask pattern is drawn.Accordingly, the electron beam pattern forming method takes more timefor exposure (drawing) as the number of patterns to be drawn increases,disadvantageously resulting in increased time for pattern formation.Thus, as the level of integration greatly increases from 256 MB to 1 GBto 4 GB, the time required for pattern formation also increases greatly,possibly resulting in significantly lowered throughput. Thus, in orderto reduce time required by the electron beam lithography equipment,development of a one-shot pattern irradiation method is underway wherebymasks of various shapes are combined and are irradiated with an electronbeam in a single shot, and electron beams of complex shapes are formed.While this allows ever finer patterns to be obtained, it also results inan increase in the size of the electron beam lithography equipment, andit requires a mechanism for controlling mask positions more accurately,thereby increasing equipment cost.

[0006] Technologies for carrying out fine pattern formation at low costare disclosed in U.S. Pat. No. 5,259,926, U.S. Pat. No. 5,772,905 and S.Y. Chou et al., Appl. Phys. Lett., vol. 67, p. 3314 (1995), for example.According to these technologies, a mold having the same concave-convexpattern of as that which is desired to be formed on a substrate isstamped on a resist film layer formed on the surface of the substrate,thereby transferring a predetermined pattern onto the substrate.Particularly, it is described in U.S. Pat. No. 5,772,905 and S. Y. Chouet al., Appl. Phys. Lett., vol. 67, p. 3314 (1995) that the disclosednanoimprint technique, using a silicon wafer as a mold, can transfer andform fine structures of not more than 25 nanometers.

SUMMARY OF THE INVENTION

[0007] However, even with the imprint technique that is supposed to becapable of forming a fine pattern, it is difficult to release a moldfrom the substrate once the mold has been pressed thereon, with highaccuracy and without deforming the fine concave-convex pattern formed onthe substrate. For example, when a silicon wafer is used as a mold, themold could be damaged upon its release.

[0008] SPIE'S Microlithography, Santa Clara, Calif., Feb. 27-28, 2001discloses that a release treatment is provided for the mold that is thenmechanically released. In this method, however, the problem of damage tothe mold upon release has not yet been solved.

[0009] In view of the foregoing, it is the object of the presentinvention to provide a nanoprint method that is a pattern transfertechnique for forming fine structures during the manufacture ofsemiconductor devices, for example, whereby the mold can be easily andaccurately released from the substrate.

[0010] The present invention is based on the understanding that one ofthe reasons preventing the efficient release of the mold is that thearrangement of the substrate and mold is too rigid.

[0011] In one aspect, the invention provides a mold for forming a finestructure on a substrate using a press machine. The mold, which is fornanoprinting, is provided with a release mechanism, which facilitatesthe release of the mold from the substrate.

[0012] The invention also provides a nanoprint mold for forming a finestructure on a substrate using a press machine, wherein a portion of aperiphery portion of said mold on the side where the concave-convexpattern is formed is inclined such that a center portion of thesubstrate has a large thickness. By increasing the thickness at thecenter portion of the mold, the substrate, which is warped during thepress process, tries to regain its original state during the releasestep, creating a stress that facilitates the release of the mold fromthe substrate. Thus, the mold can be easily released from the substrateat a point where the stress is created.

[0013] The invention also provides a nanoprint mold for forming a finestructure on a substrate using a press machine, wherein the mold isflexible. Because the mold is flexible, damage to the mold and/or thesubstrate that can occur if a local stress is applied between thesubstrate and the mold during the release step can be prevented.

[0014] Preferably, the mold is secured to a supporter via an elastomer.By thus securing the mold to the supporter via an elastomer, the forceexisting between the substrate and the mold can be made more flexible sothat damage to the substrate and/or the mold can be effectivelyprevented.

[0015] Preferably, the supporter comprises a rectangular, square,circular, or elliptical frame structure. By adopting such a framestructure, the mold can be secured to the supporter via the elastomer ina minimal manner, and further a better operability can be obtainedduring the pattern transfer by a nanoprinting method.

[0016] The invention also provides a nanoprint mold for forming a finestructure on a substrate using a press machine, wherein said mold isprovided with an elastomer at an edge of the side of said mold on whichthe concave-convex pattern is formed, said elastomer facilitating therelease of said mold from said substrate.

[0017] The press machine may comprise a heating and pressing mechanism.

[0018] In another aspect, the invention provides a pattern transfermethod for forming a fine structure on a substrate using a press machineand a nanoprint mold. A release mechanism is provided in the mold.

[0019] For example, the invention provides a pattern transfer method forforming a fine structure on a substrate using a press machine and ananoprint mold, wherein a portion of a periphery portion of said mold onthe side where the concave-convex pattern is formed is inclined suchthat a center portion of the substrate has a large thickness.

[0020] The invention also provides a pattern transfer method for forminga fine structure on a substrate using a press machine and a nanoprintmold having a heating and pressing mechanism, wherein the mold isflexible.

[0021] Preferably, the mold is secured to a supporter via an elastomer.

[0022] Preferably, the supporter comprises a rectangular, square,circular or elliptical frame structure.

[0023] A resin substrate or a resin film on a substrate is preferablymolded by either: 1) heating and deforming the resin substrate or theresin film on the substrate; 2) pressing and molding the resin substrateor the resin film on the substrate and then optically curing the resinsubstrate or the resin film; or 3) optically curing the resin substrateor the resin film on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 schematically shows individual steps of a nanoprintingprocess.

[0025]FIG. 2 shows a process of preparing a flexible mold secured to asupport frame via an elastomer.

[0026]FIG. 3 shows a process of preparing a flexible mold secured to asupport frame via an elastomer.

[0027]FIG. 4 shows a nanoprinting process utilizing a mold according tothe invention.

[0028]FIG. 5 shows a process of preparing a curved-surface mold.

[0029]FIG. 6 shows a process of preparing a curved-surface mold.

[0030]FIG. 7 shows a process of preparing a curved-surface mold.

[0031]FIG. 8 shows a convex-surface mold having a deep groove.

[0032]FIG. 9 shows a process of molding with the convex-surface moldwith deep groove.

[0033]FIG. 10 shows a concave-surface mold having a deep groove.

[0034]FIG. 11 shows a process of preparing a mold provided with anelastomer at an edge thereof.

[0035]FIG. 12 shows a process of preparing a mold provided with anelastomer at an edge thereof.

[0036]FIG. 13 shows a process of molding with a light-transmitting,flexible mold that is secured to a support frame via an elastomer.

[0037]FIG. 14 schematically shows a biochip.

[0038]FIG. 15 is a cross-sectional perspective view of the biochip nearwhere a molecular filter is formed.

[0039]FIG. 16 is a cross section of the molecular filter.

[0040]FIG. 17 shows the individual steps of a process of preparing amultilayer wiring board.

[0041]FIG. 18 is an overall view of a magnetic recording medium, with aportion thereof enlarged and shown in cross section.

[0042]FIG. 19 illustrates a method of forming a concave-convex patternon glass by a nanoprinting method, showing cross-sectional views of theglass taken along the radius thereof.

[0043]FIG. 20 schematically shows an optical circuit 500.

[0044]FIG. 21 schematically shows the layout of projections in anoptical waveguide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Referring to FIG. 1, the nanoprint method will be described. Amold is produced by forming a fine pattern on the surface of a siliconsubstrate, for example. On another substrate, there is provided a resinfilm (FIG. 1(a)). Using a press machine, not shown, equipped with aheating and pressing mechanism, the mold is pressed on the resin film attemperature exceeding the glass-transition temperature (Tg) of the resinand at a predetermined pressure (FIG. 1(b)). After cooling and hardening(FIG. 1(c)), the mold is released from the substrate, transferring thefine pattern of the mold onto the resin film on the substrate (FIG.1(d)). Alternatively, instead of the heat-molding step, aphotopolymerizing resin may be used, which can be irradiated with lightafter molding and cured. Further alternatively, a light-transmittingmold made of glass, for example, may be used, such that the resin can beirradiated with light shone from above the light-transmitting mold afterpressing and cured.

[0046] The nanoprint method offers various merits. For example: 1) itcan transfer extremely fine integrated patterns with high efficiency; 2)it can reduce equipment cost; and 3) it can be used for complex shapesand is capable of forming pillars.

[0047] Fields of application of the nanoprint method are many,including: 1) various bio-devices such as DNA chips and immunoassaychips, particularly disposable DNA chips; 2) semiconductor multilayerwiring; 3) printed circuit boards and RF MEMS; 4) optical or magneticstorage; 5) optical devices, such as waveguides, diffraction gratings,microlenses and polarizers, and photonic crystals,; 6) sheets; 7) LCDdisplays; and 8) FED displays. The present invention can be suitablyapplied to any of these fields.

[0048] The term “nanoprint” herein refers to the transfer of patterns orthe like measuring several 100 μm to several nm.

[0049] While the press machine used in the present invention is notparticularly limited, it is preferable to employ a machine equipped witha heating and pressing mechanism and/or a mechanism for shining lightfrom above the light-transmitting mold, from the viewpoint of efficientpattern transfer.

[0050] In the invention, the method of forming the fine pattern on themold that is to be transferred is not particularly limited. For example,photolithography, electron beam lithography, or other techniques may beemployed, depending on the desired processing accuracy. The material forthe mold may be any material as long as it has a desired strength and arequired level of workability, such as silicon wafer, various metalmaterials, glass, ceramics and plastics. More specifically, examplesinclude Si, SiC, SiN, polycrystalline Si, glass, Ni, Cr, Cu andcombinations thereof.

[0051] The material for the substrate used in the present invention isnot particularly limited, the only requirement being that it has arequired strength. Examples include silicon, various metal materials,glass, ceramics and plastics.

[0052] The resin film onto which the fine structure is transferred inthe invention is not particularly limited and may be selected from avariety of examples depending on the desired processing accuracy. Theexamples include thermoplastic resins such as: polyethylene,polypropylene, polyvinyl alcohol, polyvinylidene chloride, polyethyleneterephthalate, polyvinyl chloride, polystyrene, ABS resin, AS resin,acrylic resin, polyamide, polyacetal, polybutylene terephthalate,glass-reinforced polyethylene terephthalate, polycarbonate, denaturedpolyphenylene ether, polyphenylene sulfide, polyetheretherketone, liquidcrystal polymer, fluororesin, polyarylate, polysulfone,polyethersulfone, polyamide-imide, polyetherimide and thermoplasticpolyimide; and thermosetting resins such as phenol resin, melamineresin, urea resin, epoxy resin, unsaturated polyester resin, alkydresin, silicone resin, diallyl phthalate resin, polyaminobismaleimideand poly-bis-amide-triazole; and materials in which two or more of theabove-mentioned materials are blended.

EXAMPLES Examples of the invention will be hereafter described. Example1

[0053] Referring to FIGS. 2 and 3, the method of producing a moldaccording to an embodiment of the invention will be described, which isflexible and fixed to a support frame via an elastomer. It should benoted that FIGS. 2 and 3 are conceptual diagrams in which pattern shapesare simplified and enlarged. Initially, an Si substrate 1 measuring 100mm in length×100 mm in width×0.5 mm in thickness was prepared, as shownin FIG. 2(a). Then, a photoresist 2 (OEBR1000, manufactured by TokyoOhka Kogyo Co., Ltd.) for electron beam exposure was applied, using aspin coater, as shown in FIG. 2(b). Thereafter, using a JBX6000FSelectron beam lithography apparatus (manufactured by Nippon Denshi), apattern was directly drawn on the photoresist by an electron beam 3, asshown in FIG. 2(c), thus exposing the resist. The photoresist was thendeveloped to obtain convex and concave portions formed on the substrate,as shown in FIG. 2(d). The remaining resist had circular patterns, eachwith a diameter of 100 nm, arranged in a matrix at a 150 nm pitch.Alternatively, if the pattern is on the order of several 100 nm or more,a Kr laser (wavelength 351 nm) may be used instead of electron beam.Using the concave and convex portions shown in FIG. 2(d) as a maskpattern, the Si substrate 1 was dry-etched such that concave and convexportions were formed in the Si substrate 1 as shown in FIG. 2(e). Theresist 2 was then removed by O₂ ashing, thereby obtaining a master madeof silicon on one surface of which columnar projections with diametersof 100 nm were formed. On the surface of this master was then depositedNi to a thickness of several 10 nm by sputtering, as shown in FIG. 2(f).This was followed by the formation of an Ni-plated layer to a thicknessof 100 μm, as shown in FIG. 2(g). The steps (f) and (g) mayalternatively employ electroless plating. Finally, the Si master wasreleased to obtain an Ni mold in which openings with 100 nm diameterswere formed in a matrix. This Ni mold was thin and flexible. Because theconvex-concave pattern on the Ni mold is reversed from that of thesilicon master, the master must be made with a reversed pattern inadvance. Alternatively, instead of making the mold directly from thesilicon master, the silicon master pattern may be transferred to asub-master and then an Ni mold may be made from the sub-master.

[0054]FIG. 3(a) is a perspective view of an Ni mold 6 formed by theabove-described method. A elastomer 7 made of silicone rubber with ahollow center and a thickness of 1 mm was affixed to the back surface ofthe mold 6, using a silicone adhesive (KE1820, manufactured by Shin-EtsuSilicones), as shown in FIG. 3(b). Further, a supporter 8 made of a SUSframe was affixed, as shown in FIG. 3(c), thereby obtaining the moldaccording to the invention. The elastomer 7 and supporter 8 may beformed in various shapes in accordance with the shape of the mold, suchas square, rectangular, circular or elliptical shapes.

[0055] Now referring to FIG. 4, the nanostamping process using the moldof the invention will be described. FIG. 4(a) shows the mold, which isbonded to the SUS frame via resilient material, having been set on an Sisubstrate on which a 10 weight-percent diethylene glycol monoethyl etheracetate solution of polystylene 679 (manufactured by A & M Styrene Co.,Ltd.) was spin-coated. The pressure is then reduced to 0.1 Torr or less,and the mold is heated to 250° C. and maintained under the pressure of12 MPa, as shown in FIG. 4(b) for 10 minutes, thus deforming thepolystylene. Thereafter, the mold was allowed to stand to cool totemperature of less than 100° C., and then exposed to the atmosphere.This was followed by a releasing step which, if the conventionalreleasing method had been utilized, would have required a large force torelease the mold from the substrate because of the mesh between the moldand substrate via nanoscale irregularities, and would have likelydamaged the mold. In accordance with the invention, a hook was attachedto one end of the support frame, as shown in FIG. 4(c), and the supportframe was raised using the hook. As a result, the elastomer extended ina direction along its thickness, as shown in FIG. 4(d), thereby exertinga force on the Ni portion to release it from the resin. Because of therelease-start point provided at the edge of the mold, the releasingprocess proceeded smoothly, as shown in FIG. 4(e). The support frametended to break off or become damaged upon application of force in thereleasing direction in the absence of the resilient material and withthe Ni portion directly fixed to the support frame. However, inaccordance with the mold structure of the invention, the mold can bereleased without being damaged because of the provision of theelastomer.

Example 2

[0056] Referring to FIGS. 5 to 7, a method of producing a curved moldaccording to another embodiment of the invention will be described.

[0057] The Ni mold (6 inches, 100 μm in thickness) produced by theabove-described process was bonded to an SUS (6 inches, with a thicknessof 1 cm at the center and 7 mm at the edges) using a silicone adhesive(KE1820, manufactured by Shin-Etsu Silicones), and a pressure wasexerted thereon (FIG. 5(a)), thereby obtaining a convex mold (FIG.5(b)). It is possible to form a concave mold in a similar manner (FIG.6).

[0058] Alternatively, it is possible to make a curved mold by performingAu 20-nm sputtering on a concave mold, conducting Ni electroplatinguntil the center portion has a thickness of approximately 1 cm, and thenreleasing the deposited mold from the concave mold. Further, it is alsopossible to produce a concave mold by providing Ni plating on a convexmold in a similar manner.

[0059] Hereafter, the stamping process using a convex mold will bedescribed by referring to FIG. 7. A 10% diethylene glycol monoethylether acetate solution of a 500-nm thickness polystylene 679(manufactured by A & M Styrene Co., Ltd.) was applied to a 5-inch φ Sisubstrate with a 0.5-mm thickness. A 4-inch φ buffer material with a 3mm thickness was placed beneath, as shown in FIG. 7(a). The pressure wasreduced to 0.1 Torr or less, and the mold was heated to 250° C. andpressed at 12 MPa for 10 minutes. The mold was then allowed to stand tocool to temperatures 100° C. or less, when it was exposed to theatmosphere (FIG. 7(b)). When the sample was taken out and the buffermaterial was removed, the warped substrate tended to regain its originalshape and, as a result, the edge portions were easily released. When theedge portions were fixed by a jig and the mold was lifted up verticallyat the rate of 0.1 mm/s (FIG. 7(c)). The mold was easily released.

Example 3

[0060] A method of producing a mold with a curved surface in which adeep groove is formed according to another embodiment of the inventionwill be described by referring to FIGS. 8 to 10.

[0061] A cross-shaped pattern with a width of 10 μm and a depth of 3 μmwas formed in advance at the center of a Ni mold (6 inches, 100 μm inthickness). The mold was then bonded to an SUS (6 inches, with athickness of 1 cm at the center and 7 mm at the edges), with a siliconeadhesive (KE1820, manufactured by Shin-Etsu Silicones), therebyobtaining a deep-grooved convex mold (FIG. 8).

[0062] A stamping process was carried out using the above-describedconvex-curved mold with the deep groove. A 10% diethylene glycolmonoethyl ether acetate solution of polystyrene 679 (manufactured by A &M Styrene Co., Ltd.) was applied to a 5-inch φ Si substrate with athickness of 0.5 mm, to a thickness of 500 nm. A 4-inch φ buffermaterial of a thickness of 3 mm was then placed underneath. The base ofthe press machine had been formed to have a concave-curved surface inadvance (FIG. 9(a)). The pressure was then reduced to 0.1 Torr or less,and the mold was heated to 250° C. and then pressed at 12 MPa for 10minutes. As a result, the substrate was smoothly bent in conformity withthe curvature of the base (FIG. 9(b)). The mold was then allowed tostand to cool to temperature of 100° C. or less when it was exposed tothe atmosphere. The sample was then put out and the buffer material wasremoved. As the warped substrate tended to regain its original shape,the edge portions of the substrate were released by themselves. Further,air was introduced to the deep groove at the center of the substratewhere another release-start point was provided. With the edge portionsof the substrate secured by a jig, the mold was lifted vertically at therate of 0.1 mm/s (FIG. 9(c)). The mold was easily released.

[0063] Similar effects were obtained with a concave-curved mold with adeep groove as shown in FIG. 10.

Example 4

[0064] A method of producing a mold with elastic edges according toanother embodiment of the invention will be described by referring toFIGS. 11 and 12.

[0065] A stepped Ni mold (4-inch φ, with a 1-cm band portion at theperiphery measuring 1 mm in thickness, a pattern-formed portionmeasuring 5 mm in thickness, and a pattern measuring 300 nm in depth)was affixed to an SUS frame (6-inch φ; 1 mm in thickness), using asilicone adhesive (KE1820, Shin-Etsu Silicones). A silicone rubbermember (6 mm square in cross section) was affixed to the periphery ofthe mold using the aforementioned adhesive.

[0066] A 10% diethylene glycol monoethyl ether acetate solution ofpolystyrene 679 (manufactured by A & M Styrenes) was applied to a 5-inch+Si substrate with a 0.5 mm thickness to a thickness of 500 nm (FIG.11(a)). The pressure was then reduced to 0.1 Torr or less, and the moldwas heated to 250° C. and pressed at 12 MPa for 10 minutes, thuscompressing the silicone rubber. The mold was then allowed to stand tocool, and exposed to the atmosphere at 100° C. or less (FIG. 11(b)).When the molding pressure was removed, the compressed silicone rubber,in an attempt to regain its original shape, exerted a force in areleasing direction such that a release-start point existed at the edgeof the mold. With the Si substrate vacuum-sucked, the mold was liftedvertically at the rate of 0.1 mm/s (FIG. 11(c)). The mold was easilyreleased.

[0067] Similar effects were obtained when an elastomer was affixed to aNi mold provided with a tapered edge, as shown in FIG. 12.

Example 5

[0068] Referring to FIG. 13, a molding process using a flexible,light-transmitting mold secured to a support frame via an elastomeraccording to another embodiment of the invention will be described.

[0069] A silicone rubber member as an elastomer with a hollow center andwith a thickness of 1 mm was affixed to a quartz mold (VIOSIL:manufactured by Shin-Etsu Chemical Co., Ltd., 5-inch φ and 6.35 mm inthickness) using a silicone adhesive (KE1820, manufactured by Shin-EtsuSilicones). An SUS frame was further affixed as a supporter. Aphotosetting resin (SCR701, manufactured by JSR) was spin-coated on aquartz substrate (VIOSIL: Shin-Etsu Chemical Co., Ltd., 5-inch φ and6.35 mm in thickness), to a thickness of 500 nm (FIG. 13(a)). Then, thepressure was reduced to 0.1 Torr or less, and the mold was pressed at0.5 MPa for 10 minutes without heating (FIG. 13(b)). Then, the resin wasirradiated with a UV light at 100 mJ/cm² (FIG. 13(c)). After the moldwas exposed to the atmosphere, a hook was attached to the SUS frame andthe frame was lifted using the hook. The elastomer extended, and astress was concentrated at the edge of the mold, which became arelease-start point allowing a smooth release of the mold (FIG. 13(d)).

Examples of the Application of the Invention

[0070] Hereafter, several fields to which the nanoprinting techniqueusing the mold with a release-mechanism according to the invention canbe suitably applied will be described.

Example 6 Bio(Immuno)Chip)

[0071]FIG. 14 schematically shows a biochip 900. In a substrate 901 madeof glass is formed a flow passage 902 with a depth of 3 μm and a widthof 20 μm. A specimen containing DNA (deoxyribonucleic acid), blood,protein and the like is introduced via an inlet 903 and is caused toflow in the flow passage 902 until it reaches an outlet 904. A molecularfilter 905 is disposed in the flow passage 902. In the molecular filter905, there is formed a projection assembly 100 measuring 250 to 300 nmin diameter and 3 μm in height.

[0072]FIG. 15 is a cross-sectional perspective view of the biochip 905near where the molecular filter 905 is formed. The projection assembly100 is formed in a part of the flow passage 902 formed on the substrate901. The substrate 901 is covered with an upper substrate 1001 so thatthe specimen flows inside the flow passage 902. In the case of a DNAchain-length analysis, while a specimen containing DNA iselectrophoresed in the flow passage 902, DNA is separated by themolecular filter 905 depending on the chain length of the DNA with highresolution. The specimen that has passed through the molecular filter905 is irradiated with a laser light emitted by a semiconductor laser906 mounted on the surface of the substrate 901. When the DNA passes,the light incident on a photodetector 907 is reduced by about 4%, sothat the chain length of DNA in the specimen can be analyzed based on anoutput signal from the photodetector 907. The signal detected in thephotodetector 907 is fed to a signal processing chip 909 via a signalline 908. To the signal processing chip 909 is connected another signalline 910, which is also connected to an output pad 911 for connectionwith an external terminal. Power is supplied to individual componentsvia a power supply pad 912 provided on the surface of the substrate 901.

[0073]FIG. 16 shows a cross section of the molecular filter 905 which,according to the present embodiment, comprises a substrate 901 with aconcave portion, a plurality of projections formed on the concaveportion of the substrate 901, and an upper substrate 1001 formed tocover the concave portion. The projections are formed such that theirtips are in contact with the upper substrate. The projection assembly100 is mainly made of an organic material and can therefore be deformed.Thus, the projection assembly 100 is not subject to damage when theupper substrate 1001 is mounted over the flow passage 902. The uppersubstrate 1001, therefore, can be placed in contact with the projectionassembly 100. In this arrangement, highly sensitive analysis can beperformed without the specimen being leaked from the gap between theprojections and the upper substrate 1001. When a chain-length analysisof DNA was actually conducted, it was learned that while the half-valuewidth of resolution of the base pairs was 10 base pairs in the case ofthe projection assembly 100 made of glass, it was possible to improvedthe half-value width of resolution of the base pairs to 3 base pairs inthe case of the projection assembly 100 made of an organic material.While the molecular filter in the present embodiment has a structuresuch that the projections are in contact with the upper substrate, afilm made of the same material as that of the projections may be formedon the upper substrate such that the projections are in contact with thefilm. In this way, better contact can be obtained.

[0074] While in the present embodiment there is only one flow passage902, a plurality of flow passages 902 in which projections of differentsizes are disposed may be provided. In this way, different kinds ofanalysis can be performed simultaneously.

[0075] While in the present embodiment DNA was examined as specimen, aparticular sugar chain, protein or antigen may be analyzed by modifyingthe surface of the projection assembly 100 in advance with a moleculethat reacts with the sugar chain, protein or antigen. By thus modifyingthe surface of the projections with an antibody, improvements can bemade in the sensitivity of immunoassay.

[0076] By applying the invention to a biochip, a projection for theanalysis of organic materials with nanoscale diameters can be simplyformed. Further, by controlling the shapes of the concave and convexportions on the mold surface or the viscosity of the organic materialthin film, the position, diameter and/or height of the projection madeof organic material can be controlled. Thus, in accordance with theinvention, there can be provided a microchip for high-sensitivityanalysis.

Example 7 Multilayered Wiring Board

[0077]FIG. 17 shows the process of making a multilayered wiring board.After a resist 702 is formed on the surface of a multilayer wiring board1001 comprising a silicon oxide film 1002 and copper wiring 1003, asshown in FIG. 17(a), a pattern transfer process is carried out using amold (not shown). Exposed regions 703 on the multilayer wiring board1001 are then dry-etched using CF₄/H₂ gas. As a result, the exposedregions 703 on the surface of the multilayer wiring board 1001 areprocessed in the shape of grooves, as shown in FIG. 17(b). The resist702 is then resist-etched by RIE to thereby remove the resist at thelower-step portions, so that the exposed regions 703 are enlarged, asshown in FIG. 17(c). Thereafter, the exposed regions 703 are dry-etcheduntil the previously formed grooves reach the copper wiring 1003,thereby obtaining a structure as shown in FIG. 17(d). The resist 702 isthen removed to obtain the multilayer wiring board 1001 having a groovedsurface, as shown in FIG. 17(e). On the surface of the multilayer wiringboard 1001 is then formed a metal film by sputtering (not shown),followed by electroplating, thereby forming a metal-plated film 1004 asshown in FIG. 17(f). The metal-plated film 1004 is then polished untilthe silicon oxide film 1002 on the multilayer wiring board 1001 isexposed, thus obtaining the multilayer wiring board 1001 with metalwiring formed on the surface thereof, as shown in FIG. 17(g).

[0078] Another process for making a multilayer wiring board will behereafter described. Upon dry-etching of the exposed regions 703 in thestate shown in FIG. 17(a), by etching until the copper wiring 1003inside the multilayer wiring board 1001 is reached, the structure shownin FIG. 17(h) is obtained. The resist 702 is then etched by RIE toremove the resist on the lower-step portions, thereby obtaining thestructure shown in FIG. 17(i). Thereafter, a metal film 1005 is formedon the surface of the multilayer wiring board 1001 by sputtering, sothat the structure shown in FIG. 170) is obtained. The resist 702 isthen lifted and removed, thereby obtaining the structure shown in FIG.17(k). By conducting electroless plating using the remaining metal film1005, the multilayer wiring board 1001 can be obtained with thestructure shown in FIG. 17(l).

[0079] By applying the invention to a multilayer wiring board, wires canbe formed with high dimensional accuracy.

Example 8 Magnetic Disc

[0080]FIG. 18 shows an overall view of a magnetic recording mediumaccording to Example 8, with a portion enlarged and shown in crosssection. The substrate is made of glass having fine concave and convexportions. On the substrate are formed a seed layer, a base layer, amagnetic layer, and a protective layer. Now referring to FIG. 19, themethod of manufacturing a magnetic recording medium according to thepresent example will be described. FIG. 19 shows a radial cross sectionof the substrate, illustrating a method of forming concave and convexportions on the glass by a nanoprinting method. First, a glass substrateis prepared. A soda lime glass was used in the present example. Thematerial of the substrate is not particularly limited, with the onlyrequirement being that it can be formed as sheets. Examples includeother glass materials such as aluminosilicate glass, and metal materialssuch as Al. Then, a resin film was formed to a thickness of 200 nm usinga spin coater, as shown in FIG. 19(a). The resin was PMMA (polymethylmethacrylate).

[0081] For the mold, a Si wafer was prepared in which grooves wereformed concentrically with the opening at the center of the magneticrecording medium. The grooves measured 88 nm in width and 200 nm indepth, and the pitch between the grooves was 110 nm. The convex andconcave portions of the mold, which were very fine, were formed byphotolithography using an electron beam. After heating the mold to 250°C. to reduce the viscosity of the resin, as shown in FIG. 19(b), themold was pressed. When the mold was released at a temperature below theglass-transition point of glass, a reversed concave-convex pattern tothe pattern on the mold was obtained, as shown in FIG. 19(c). Thus,using the nanoprinting method, a pattern can be formed that is finerthan visible light wavelength and beyond the dimensional limit ofexposure by conventional photolithography. Further, by removing theremaining film at the bottom of the resin pattern by dry etching, apattern as shown in FIG. 19(d) can be formed. By further etching thesubstrate with hydrofluoric acid using this resin film as a mask, thesubstrate can be processed as shown in FIG. 19(e). By removing the resinwith a remover, grooves with a width of 110 nm and a depth of 150 nmwere formed, as shown in FIG. 19(f). Thereafter, a seed layer made ofNiP was formed on the glass substrate by electroless plating. In theconventional magnetic discs, the NiP layer is formed to a thickness of10 μm or more. In the present embodiment, the thickness of the NiP layerwas limited to 100 nm in order to reflect the fine concave and convexshapes formed on the glass substrate onto the upper layer. Further, a Crbase layer of 15 nm, a CoCrPt magnetic layer of 14 nm, and a Cprotective layer of 10 nm were successively formed by a sputteringmethod generally employed in forming magnetic recording media, therebypreparing the magnetic recording medium according to the presentembodiment. In this magnetic recording medium, the magnetic substancewas radially isolated by a non-magnetic layer wall with a width of 88nm. Thus, a higher longitudinal magnetic anisotropy was obtained. Whilethe formation of concentric patterns using a polishing tape (texturing)is known in the art, it can only offer a pattern pitch on the order ofmicrons and is therefore not suitable for high-density recording media.In the magnetic recording medium of the present embodiment, on the otherhand, magnetic anisotropy was ensured by forming a fine pattern by thenanoprinting method, and a high-density recording of 400 GB per squareinch was achieved. The nanoprinting pattern formation technique is notlimited to the circumferential direction, but it can also be used forradially forming a non-magnetic isolating wall. Further, the effect ofthe present embodiment whereby the magnetic anisotropy is provided isnot particularly limited by the materials used in the seed layer, baselayer, magnetic layer or protective layer.

Example 9 Optical Waveguide

[0082] Another example will be described in which an optical device withvarying directions of propagation of incident light is applied to anoptical information processing apparatus.

[0083]FIG. 20 schematically shows the structure of an optical circuit500 that was prepared. The optical circuit 500 comprised a substrate 501of aluminum nitride, measuring 30 mm in length, 5 mm in width and 1 mmin thickness. On the substrate 501 were formed ten transmission units502 each consisting of an InP semiconductor laser and a driver circuit,an optical waveguide 503 and an optical connector 504. The tensemiconductor lasers have different transmission wavelengths varying at50 nm intervals. The optical circuit 500 is a basic component in opticalmultiplex communication system devices.

[0084]FIG. 21 schematically shows the layout of projections 406 insidethe optical waveguide 503. In order to allow for an alignment errorbetween the transmission unit 502 and the optical waveguide 503, theoptical waveguide 503 was formed to be wider toward the end that had awidth of 20 μm. Thus, the waveguide had a structure such that a signallight was guided into a region with a width of 1 μm by a photonicbandgap. While the projections 406 were arranged at 0.5 μm intervals inthe actual device, the projections 406 in FIG. 21 are shown in asimplified manner and fewer of them are shown than actually existed.

[0085] In the optical circuit 500, the directions of propagation oflight can be varied when ten different wavelengths of signal light aresuperposed and outputted, so that the width of the circuit can begreatly reduced, to 5 mm in the example. Thus, the size of the opticalcommunication device can be reduced. The projections 406 can be formedby the pressing of a mold, and manufacturing cost can be reduced. Whilethe present example relates to a device in which input light issuperposed, it should be obvious that the optical waveguide 503 can beusefully applied to all optical devices for controlling an optical path.

[0086] By applying the present invention to optical waveguides, thedirection of propagation of light can be varied by causing a signallight to propagate in a structure where projections made of an organicmaterial as a principal component are periodically arranged. Theprojections can be formed by a simple manufacturing technique involvingthe pressing of a mold, such that an optical device can be manufacturedat low cost.

[0087] In accordance with the invention, a release mechanism is providedin a nanoprint mold by, in particular, increasing the thickness of acenter portion of the mold. By so doing, the substrate is warped duringthe pressing step and then tries to regain its original state as themold is released in the release step, creating a stress causing thesubstrate and mold to separate from each other. Thus, the release of themold from the substrate is facilitated at a point where the stressexists. Further, in accordance with the invention, a flexible mold isemployed such that the damage to the substrate and/or the mold thatcould result if a local stress is applied between them during thereleasing of the mold can be prevented. In accordance with theinvention, additionally, a spring mechanism is provided between the moldand the substrate whereby the release of the mold from the substrate isfacilitated during the release step.

What is claimed is:
 1. A nanoprint mold for forming a fine structure ona substrate with the use of a press machine, said mold comprising arelease mechanism.
 2. The nanoprint mold according to claim 1, whereinsaid mold is provided with a curved surface on the side thereof on whicha concave-convex pattern is formed.
 3. The nanoprint mold according toclaim 2, wherein a portion of a periphery portion of said mold on theside where the concave-convex pattern is formed is inclined such that acenter portion of the substrate has a large thickness.
 4. The nanoprintmold according to claim 2, wherein a portion of a periphery portion ofsaid mold on the side on which the concave-convex pattern is formed isinclined such that a center portion of the substrate has a smallthickness.
 5. The nanoprint mold according to claim 2, wherein the sideof said mold on which the concave-convex pattern is formed is providedwith a curved surface and is also provided with a deep groove at aportion thereof.
 6. The nanoprint mold according to claim 1, whereinsaid press machine comprises a heating and pressing mechanism.
 7. Thenanoprint mold according to claim 1, wherein said mold has alight-transmitting property.
 8. The nanoprint mold according to claim 1,wherein said mold is flexible.
 9. The nanoprint mold according to claim8, wherein said mold is secured to a supporter via an elastomer.
 10. Thenanoprint mold according to claim 9, wherein said supporter comprises arectangular, square, circular or elliptical frame structure.
 11. Thenanoprint mold according to claim 1, wherein said mold is provided withan elastomer at an edge of the side of said mold on which theconcave-convex pattern is formed, said elastomer facilitating therelease of said mold from said substrate.
 12. A pattern transfer methodfor forming a fine structure on a substrate with the use of a pressmachine and a nanoprint mold, wherein said mold comprises a releasemechanism.
 13. The pattern transfer method according to claim 12,wherein said mold is provided with a curved surface on the side thereofon which a concave-convex pattern is formed.
 14. The pattern transfermethod according to claim 13, wherein a portion of a periphery portionof said mold on the side where the concave-convex pattern is formed isinclined such that a center portion of the substrate has a largethickness.
 15. The pattern transfer method according to claim 13,wherein a portion of a periphery portion of said mold on the side onwhich the concave-convex pattern is formed is inclined such that acenter portion of the substrate has a small thickness.
 16. The patterntransfer method according to claim 13, wherein the side of said mold onwhich the concave-convex pattern is formed is provided with a curvedsurface and is also provided with a deep groove at a portion thereof.17. The pattern transfer method according to claim 12, wherein a patternis transferred by heating and thereby deforming a resin substrate or aresin film on a substrate.
 18. The pattern transfer method according toclaim 12, wherein a pattern is transferred by pressing and molding aresin substrate or a resin film on a substrate and then photo-curingsaid resin substrate or resin film.
 19. The pattern transfer methodaccording to claim 12, wherein a pattern is transferred by irradiating aresin substrate or a resin film on a substrate with light from above atransparent mold such that said resin substrate or resin film isphoto-cured.
 20. The pattern transfer method according to claim 12,wherein said mold is flexible.
 21. The pattern transfer method accordingto claim 20, wherein said mold is secured to a supporter via anelastomer.
 22. The pattern transfer method according to claim 21,wherein said supporter comprises a rectangular, square, circular orelliptical frame structure.
 23. The pattern transfer method according toclaim 12, wherein said mold is provided with an elastomer at an edge ofthe side of said mold on which the concave-convex pattern is formed,said elastomer facilitating the release of said mold from saidsubstrate.